Your installation must be defective!
I have a Mac, and I'm typing this on it while using TurboC++.
Consider uninstalling and then reinstalling the programme.
Download the package in the same way as you would a.dmg programme from the internet.
(For example, drag and drop the programme into the Applications folder)
Ascertain that your Applications folder is global to your system.
This is what I mean:
When in Finder, select the "GO" option from the top menu bar.
From the drop down option, choose "Computer."
In the newly opened window, click on your hard disc.
There is a "Applications" folder there.
That's where you should put TurboC++.
Go to Launchpad, and start Turbo C++. Then type the following commands:
mount c: /Applications/TurboC++
It is case sensitive so be careful.
This is how it should look: